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Biomedical subjects

S Mallik

Publications and source records attributed to S Mallik.

At least 19 recordsLinked to original sources
PubMed2005

Effect of heat treatment on the physico-chemical properties and catalytic activity of manganese nodules leached residue towards decomposition of hydrogen peroxide.

The effect of calcination temperature on the physico-chemical characterization of manganese nodule leached residue (MNLR) and water-washed manganese nodule leached residue (WMNLR) has been investigated on the basis of chemical analysis, XRD, TG-DTA, FTIR, surface hydroxyl groups, surface oxygen, reducing and oxidizing sites, surface area. XRD and IR confirm the presence of amorphous iron oxyhydroxides, delta-MnO2, which are converted to alpha-Fe2O3 and gamma-Mn2O3 phases above 400 degrees C of calcination, respectively. A solid solution of Fe2O3 and Mn2O3 is formed above 700 degrees C. The surface area, surface hydroxyl group, surface oxygen, reducing and oxidizing sites increase with the increase in calcination temperature up to 400 degrees C and then decrease with further rise in calcination temperature up to 700 degrees C. The catalytic activity of the sample towards H2O2 decomposition shows the similar trend as surface properties. A suitable Mn(3+)Mn4+ couple favours H2O2 decomposition reaction. The activity has been correlated with various physico-chemical properties.

Catalysis↗
PubMed2005

Studies on manganese nodule leached residue 4. Physicochemical characterization and catalytic activity of acetic acid treated manganese nodule leached residue.

The catalytic activity of water-washed manganese nodule leached residue (WMNLR) samples improved by treating with acetic acid. The effects of acetic acid treatment on the physicochemical properties and catalytic activity of manganese nodule leached residue have been studied. The surface area, surface oxygen, surface hydroxyl groups, surface acidity, electron donating properties, etc., increase gradually with acid treatment up to 0.5 M and thereafter show a decreasing trend. The rate constant of H2O2 decomposition, catalytic activity of CO oxidation, and esterification of acetic acid also show a similar trend to that of surface properties.

Journal Article↗
PubMed2001

Surface recognition of a protein using designed transition metal complexes.

Each protein has a unique pattern of histidine residues on the surface. This paper describes the design, synthesis, and binding studies of transition metal complexes to target the surface histidine pattern of carbonic anhydrase (bovine erythrocyte). When the pattern of cupric ions on a complex matches the surface pattern of histidines of the protein, strong and selective binding can be achieved in aqueous buffer (pH = 7.0). The described method of protein recognition is applicable to proteins of known structures. With rapidly increasing number of solved protein structures, the method has wide applicability in purification, targeting, and sensing of proteins.

Animals↗
PubMed2001

Synthesis of conjugated diacetylene, metal-chelating monomers for polymerizable monolayer assemblies.

[see structure]. Self-assembled monolayers (SAMs) of thiols on gold have been used for numerous applications. For protein targeting applications, one successful strategy is to use a metal-chelating SAM. It has also been demonstrated that polymerized SAMs are much more stable than non-polymerized counterparts. We report herein, the synthesis of several polymerizable, metal-chelating thiols capable of complexing luminescent lanthanide ions.

Acetylene↗
PubMed2000

Polymerized fluorescent liposomes incorporating lanthanide ions.

This paper describes the design and synthesis of a polymerizable lipid capable of complexing lanthanide ions. The lipid has been successfully incorporated into liposomes and then polymerized. Fluorescence studies indicate that the diacetylene (unpolymerized lipid) and the conjugated alkenes (after polymerization) can be used as sensitizers for the lanthanide ion.

Chelating Agents↗
PubMed2000

Synthesis and fluorescence properties of new fluorescent, polymerizable, metal-chelating lipids.

Liposomes incorporating fluorescent, metal-chelating lipids find applications in molecular recognition of peptides, 2D protein recrystallization, protein targeting, and biological sensing. It would be advantageous to combine the usefulness of polymerizable, metal-chelating lipids and fluorescent lipids. Herein, we report the synthesis and fluorescence properties of several fluorescent, polymerizable, metal-chelating lipids. They have been successfully incorporated into liposomes and then polymerized. These lipids can be used as membrane probes to study the polymerizable liposomes in the unpolymerized state and to investigate lipid redistribution during polymerization. In addition, if a luminescent metal ion (e.g., Eu(3+), Tb(3+), etc.) is used to complex the headgroup, the lipids can probe the membrane interior and exterior simultaneously.

Chelating Agents↗
PubMed2000

Recognition of flexible peptides in water by transition metal complexes.

This paper describes the design, synthesis, and evaluation of transition metal complexes capable of recognizing flexible histidine-containing peptides in aqueous medium (25 mM HEPES buffer, pH = 7.0, 25 degrees C). When the pattern of metal ions on a complex matches with the pattern of histidine moieties on the peptide, strong interaction (K = 1.2 x 10(6) M-1) can be achieved. The complex was highly selective (> 200:1) in discriminating similar flexible peptides differing only by one glycine unit.

Glycine↗
PubMed2000

Fibrobacter succinogenes S85 ferments ball-milled cellulose as fast as cellobiose until cellulose surface area is limiting.

Fibrobacter succinogenes S85 grew rapidly on cellobiose (0.31 h(-1) and the absolute rate of increase in fermentation acids was 0.68 h(-1). Cultures that were provided with ball-milled cellulose initially produced fermentation acids and microbial protein as fast as those provided with cellobiose, but the absolute cellulose digestion rate eventually declined. If the inoculum size was increased, the kinetics decayed from first to zero order (with respect to cells) even sooner, but in each case the absolute rate declined after only 20 to 30% of the cellulose had been fermented. Congo red binding indicated that the cellulose surface area of individual cellulose particles was not decreasing, and the transition of ball-milled cellulose digestion corresponded with the appearance of unbound cells in the culture supernatant. When bound cells from partially digested cellulose were removed and the cellulose was re-incubated with a fresh inoculum, the initial absolute fermentation rate was as high as the one observed for undigested cellulose and cellobiose. Based on these results, cellulose digestion by F. succinogenes S85 appears to be constrained by cellulose surface area rather than cellulase activity per se.

Animals↗
PubMed2000

Respiratory syncytial virus upper respiratory tract illnesses in adult blood and marrow transplant recipients: combination therapy with aerosolized ribavirin and intravenous immunoglobulin.

Respiratory syncytial virus (RSV) is an important cause of serious respiratory illness in blood and marrow transplant (BMT) recipients. In some subsets of these immunocompromised patients, RSV upper respiratory illnesses frequently progress to fatal viral pneumonia. The frequency of progression to pneumonia is higher during the pre-engraftment than during the post-engraftment period. Once pneumonia develops, the overall mortality is 60-80%, regardless of the treatment strategy. We performed a pilot trial of therapy of RSV upper respiratory illnesses using aerosolized ribavirin and IVIG (500 mg/kg every other day), with the goal of preventing progression to pneumonia and death. Two dosages of ribavirin were used: a conventional regimen (6 g/day at 20 mg/ml for 18 h/day) and a high-dose short-duration regimen (6 g/day at 60 mg/ml for 2 h every 8 h). Fourteen patients were treated for a mean of 13 days (range: 7-23 days). In 10 (71%) patients, the upper respiratory illness resolved. The other four (29%) patients, three of whom were in the pre-engraftment period, developed pneumonia, which was fatal in two. The most common adverse effect was psychological distress at being isolated within a scavenging tent. In conclusion, prompt therapy of RSV upper respiratory illnesses in BMT recipients with a combination of aerosolized ribavirin and IVIG was a safe and promising approach to prevent progression to pneumonia and death.

Adult↗
PubMed1994

Unifocal Langerhans' cell histiocytosis (eosinophilic granuloma) resembling Ewing's sarcoma.

In a 9 year old boy, a destructive lesion in the diaphysis of the right femur was wrongly diagnosed as a Ewing's sarcoma on the basis of the radiologic findings and fine needle aspiration cytology report. The clinical and radiologic picture was suggestive of Ewing's sarcoma, but an open biopsy of the lesion revealed a histopathological pathological picture of eosinophilic granuloma. A brief review of the literature is given, together with discussion on the differential diagnosis of a mid shaft femoral lesion in young patients.

Bone Diseases↗